The Wall Street Journal reports: TEL AVIV—An Israeli government watchdog on Tuesday released a highly critical report into Prime Minister Benjamin Netanyahu’s travel expenses while he was finance minister more than a decade ago, and raised the possibility of a criminal investigation.

In the report, State Comptroller Yosef Shapira said Mr. Netanyahu had failed to tell a parliamentary committee that numerous trips he and family members took between 2003 and 2005 were paid for by private individuals and organizations. Those payments created the appearance of bribery or a conflict of interest, he said—but they were common practice and would have been legal at the time because there weren’t regulations in force forbidding them.

In a separate statement, Mr. Shapira also said Mr. Netanyahu during that time also had apparently double-billed some flight expenses to both state and private bodies and had used airline bonus points, accrued by the state, for his private travel on El Al Israel Airlines. Mr. Shapira said that behavior raised the suspicion of criminal conduct.

Mr. Shapira said he referred that information to Attorney General Avichai Mandelblit, who would decide whether to launch an investigation.